The front end portion of a communication system, such as in a handset used in RF communications, typically contains multiple RF components in separate component packages. In some systems, the Gallium Arsenide (GaAs) die, the Pseudo Morphic High Electron Mobility Transistor (PHEMT) die, the Silicon (Si) die, and the passive components are typically mounted on a multi-layer laminate substrate and the assembly is encapsulated with plastic overmold.
However, the physical size of the front end in these communications systems is typically larger than is desirable, creates additional board interconnects, weighs more than is desired, and costs more than is desired due to a large and more expensive bill of materials. Moreover, due to a lack of signal isolation on current front end switches, diplexers are often required to provide additional RF isolation for the entire front end. The undesirable spurious emissions (oscillations) of power amplifiers in such systems are sensitive to the impedance mismatch at the output/antenna port.
High power amplifiers operated in saturated mode required by modern handset designs are particularly sensitive to impedance mismatching. Great care must be taken to ensure minimal spurious emissions under all operating conditions. Furthermore, the control circuitry in these systems is also susceptible to stray RF signals, due to the signal routing required when using separate components to form the front end function. This may further degrade RF isolation.
Accordingly, it would also be helpful to the art of electromagnetic processing to provide a more efficient and reliable front end portion of a communication system.